Wednesday 25 April 2012 13.00 EDT
First published on Wednesday 25 April 2012 13.00 EDT

Spiders have fantastic genitals, even in their non-extended state. Few people have ever seen an erect spider penis, though. Actually, their penises come in pairs called pedipalps: the males ejaculate onto a silk web and suck up the sperm with their pedipalps. Then they try to mate with females, a complex process that often involves a sort of high-speed dance since the females are usually twice their size – at least – and very likely to attempt to eat them.

It's a great mystery what turns a spider on, but I was lucky enough to have an arachnologist friend at the California Academy of Sciences who knew the secret: boil them in a bath of lactic acid, cool and then wait. We carried out this elaborate process, which took about an hour, on a large dead wolf spider; it would be difficult to do anything similar with a live spider, not least because you couldn't pin it down to hold its pedipalps in the desired position for a shot.

After its 3mm pedipalps had expanded, you could see all these big bulbs and structures. Scientists still don't know what some of them do. When it had stabilised, I took 60 images through a microscope at 50x magnification with a Leica camera attached. Then, on a computer, I merged them all into a composite shot: if you just saw one layer of the image, only a little hair would be in focus.

I'm sure pictures of spider erections have appeared before in scientific journals, but I added extra lighting to give the shot a romantic feel. I think evolution is one of the most beautiful art forms. Since biologists wouldn't shoot spiders in this way, it's probably the first ever artistic shot of a spider erection..

CV

Born: San Francisco, 1977

Studied: Biology at San Francisco State University. Self taught photography.